Aquarium heater



FIG. 1 is a front, right and top perspective view of an aquarium heater, showing my design.

FIG. 2 is a front elevation view thereof.

FIG. 3 is a rear elevation view thereof.

FIG. 4 is a left side elevation view thereof.

FIG. 5 is a right side elevation view thereof.

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

The broken lines shown in the drawings depict environmental structure of the aquarium heater that form no part of the claimed design. 

CLAIM The ornamental design for an aquarium heater, as shown and described. 